Throughput and delay performance of transport user in congestion controlled hybrid ATM/TDMA networks

The end-to-end throughput and delay performance characteristics are analyzed for a virtual circuit (VC) transport user in a hybrid asynchronous transfer mode/time division multiple access (ATM/TDMA) network. An automatic repeat request (ARQ) transport user is assumed with an underlying ATM cell-level global congestion control in an ATM multiplexer node. The analysis is based on the interaction of packet level control with the queue management at the ATM cell level. The transport user is assumed over M-node VC to analyze the throughput and delay using Norton equivalent queueing model. The transport layer service characteristic of the model is obtained from the end-to-end protocol efficiency of Go-Back-N (GBN) and selective repeat (SR) ARQ schemes. The ATM layer is assumed with a leaky bucket (LB), virtual leaky bucket (VLB), modified LB (mLB), or modified VLB (mVLB) congestion control scheme. A global congestion control scheme prioritizes transit traffic over local traffic, and ensures quality of service (QOS) to several classes of service. Based on the global congestion status, the transport users modulate their end-to-end flow control parameters, i.e., packet size in case of video and voice users, and window size in case of data users. The probability of cell-loss at the ATM layer is reflected at the transport layer to derive the effective throughput and delay characteristics. The mVLB scheme consistently provided better end-to-end throughput and delay performance for both GBN and SR transport users.